The pop star, who has sold more than 33 million albums in the US, is also riding high at her extended residency at Planet Hollywood in Las Vegas.

Like Kim Kardashian before her, Spears recently released a game with Glu Mobile, and she unveiled her 20th fragrance with Elizabeth Arden.

Despite her post-2008 success, Spears hasn't been in control of it, or her personal life, for those eight years. Her family decided to enact her father, Jamie, and lawyer Andrew Wallet as her conservators, or guardians. They oversee her finances and daily life.

Even so, Spears is still raking in cash and seemingly not left wanting for things to spend it on — she apparently loves Target just as much as the average person.

And it seems her sights for her career and brand are clear.

"I've been very hands-on with everything I've done since I had my children ... And it's just really important for me to understand the big picture, where everybody's coming from, what's the real purpose of this shoot and this song, or whatever it is in that moment that I'm doing.

"It's important to learn to say no. With tours and all of that stuff, there are so many aspects that go into it, it's easy to have so many people around you saying, 'Oh yes, yes, you can afford this, you can afford this,' and then all of the sudden you've spent $20 million on your stage and you're like, 'Where's my money?'

"You have to make sure that you're on top of things and know where the money's going."

She makes much of her money on the road. In 2009, Billboard reported that Spears grossed $216.2 million from her tours in the first decade of the 21st century. Her "Femme Fatale" tour in 2012 added $21.7 million — $7.3 million of which she pocketed — to that total.

In 2012, Spears was also No. 1 on Forbes' list of the highest-paid women in music, having made $58 million.

When it extended her residency, Planet Hollywood in Las Vegas upped her $310,000-a-show (nearly $15 million a year) deal to $475,000 a show — just $1,000 under what Celine Dion makes. With the total number of shows now at 140, Spears is set to bank a whopping $66.5 million a year, thanks to Vegas.

Britney Spears at the "Britney Day" event to celebrate the opening of her Las Vegas show, "Britney: Piece of Me."Ethan Miller/ Getty Images

The pop star partnered with Elizabeth Arden in 2004, and by June 2016 she had debuted her 20th fragrance. In 2012, her then 11 fragrances had reportedly earned her $1.5 billion and sold more than a million bottles in five years.

Spears using her own fragrance in the music video for her song "Perfume" from the "Britney Jean" album.Britney Spears Vevo

Her first perfume, "Curious," netted $100 million in sales after one year, according to Brandweek. In peak season, Spears sold a fragrance every 15 seconds, according to Express.

She extended her brand to include lingerie and sleepwear, which are available via her retail partner Change Lingerie and cost from $26 to $160.

In 2015, Spears took her brand to the virtual world, inking a deal with Glu Mobile to develop a free-to-play mobile game using her voice and likeness — as Kim Kardashian and Katy Perry did before her. The deal goes through 2020, with the possibility of a three-year extension.

But when it came to meals and entertainment, Spears opened her pocket a little more, spending $15,270.

She's had to spend a hefty sum as a result of her legal situation. As her conservator, her father, Jamie, gets about $130,000 a year and is also reimbursed for the rent for his office. Through the years, he has asked for increases and was approved to take 1.5% of gross revenues from the performances and merchandising of Spears' Las Vegas show.

Spears even has to pay people to make sure her conservators don't abuse their power. The court appointed Samuel Ingham III as her chief advocate. Since 2008, he has been paid $2 million in fees, in addition to the $6.9 million paid from the estate to the conservators and lawyers helping manage her affairs.

Of course, she also has to pay her staff — $57,550 went to her personnel and assistants.

But Spears likes to live in style. She's known for her many real-estate investments over the years. In 2014, the expenses for her homes in Malibu, California; Louisiana; and Thousand Oaks, California, totaled more than $960,000.